Question

a one meter long stick is held vertically on a table and source of light held at 2 meter from foot of stick wall is 5 meters from stick how long does stick appear on wall

Answer 1

Explanation:

When meter stick allowed to fall from verticle postion, its potential energy is converted to rotational energy

Lets height of the meter stick is L and mass is M.

center of mass of meter stick fall from height 1/2L

using energy conservation

Mg 1/2 L=1/2ω2 ..eq(1)

where I is a moment of inertia from one end of the meter stick I= 1/3ML^2 and ω is angular velocity .

from eq(1)

MGL/2=1/2*ML/3^2 ω^2=ML/6^2 w2

speed of other end is v=ωL

⇒v= ✓3gL

where L=1m

v=✓3g=5.4 ms-1

=5.4ms^-1